Exit roll for galvanizing pots



Patented Mar. 30, 1943 UNITED STATES PATENT OFFICE EXIT ROLL FOR GALVANIZING POTS Samuel H. Bobrov, Chicago, Ill. Application August lil, &1939,Sral No. ?89,475 Glaim. (01. 9 59.2)

The presentinvention relates to exit rolls -for galvanizing pots and the like and more particularly to rolls having a roughened surface.

An object of the present invention is the provision of exit rolls having a shot blasted or knurled surface to eliminate dirt accumulation on the surface of the rolls and thereby produce cleaner sheets.

Another object of the present'invention is the provision of roughened exit rolls in a galvanizing pot or the like so as'to produce sheets free from the usual foreign particles and surface imperfecr tions which have, in the past, been the cause of 'the high percentage of rejections in finished galvanized sheets.

Other objects and advantages will become apparent as the description proceeds and reference is had to the accompanying drawing in which:

Figure 1 is a longitudinal section of a galvanizing pot embodying the present invention;

Figure 2 is an elevation of an exit roll having a knurled surface;

Figure 3 is an elevation of an exit Koll having a shot blasted surface; and

Figure 4 is a fragmentary View illustrating a means for pressure adjustment of the exit rolls.

Undervold practice, exit rolls were grooved and, in so being, they tended to gather in and became coated with foreign particles during production by the lead and zine method. Grooved rolls con- I tain continuous uninterrupted depressions protected by two unbroken walls which, should undesirable foreign matter become lodged therein,`

would prevent ready removal of the foreign matter and restrict flow of the molten metal, and prevent efficient rinsing.

Furthermore, grooved exit rolls generally leave characteristic imprints of the grooves upon 'the sheets which detract from the surface appearance of the finished product.

However, under the present invention, these difficulties are overcome. g

In the drawing, the numeral 2 represents a conventional type galvanizing pot having entry rolls 3 of conventional design. The material 4 passes through the entry rolls and downwardly into the galvanizing pot between conventional guide construction 5 and guide rolls 6, which are supported, in any conventional manner, by the rigging housing 1, which likewise is* of conventional design. u v

At the exit end of the galvanizing pot, the

c'onventional peg rolls 8 are provided for guiding ported, in any conventional manner therein, are provided exit rolls 9. These exit rolls are provided with a roughened surface, which roughness 'is of sufficient magnitude to permit the liquid metal within the pot 2 to flow to any point on the roll surface so as to present ideal conditions for removal of attached. foreign particles therefrom by free and unhampered rinsing with the molten metal through which the roll is rotating. One form of roughened surface is clearly illustrated in Figure 2, which surface is shown as being a knurled surface. This knurled surface is provided by a knurling tool of convention'al design, so as to produce a uniform surface roughness, and while a particular design has been shown in the drawing, it is to be understood that other types of knurle'd surfaces may serve the same purpose and produce the same result desired.

In Figure 3, there is shown another form of roughened surface which, in this particular instance, is produced by shot blasting. The degree of blasting is determined by the desired uniform roughness of the roll surface.

It has been developed that, by the use of i roughened exit rolls in the galvanizing pot, certain changes have been necessary in the operation of the galvanizing step. The exit rolls 9 must be operated as loosely as possible and are mounted in bearings of conventional design; as diagrammatically shown in Figure 4, so that only s'ufficient pressure isexerted upon the exit rolls to move thesheet forward 'into the peg rolls 8,

an adjustable pressure -device for such purpose 'directed to the top side of the sheet in order to avoid staining. In certain types of galvanizing,

a duli surface is developed by subjecting the. freshly coated strip or sheet to'open flames or higher temperatures in conjunction with the use of a muflie after the sheet or stripemer'ges from' the exit rolls in order to destroy .the spangiing and develop a duli, satiny, spangle free finish. In

such cases only a small amount of sulphur should be ignited to supply a minimum amountof fumes in 'order to avoid unnecesary brightening' of the coating on the strip or sheet. p

In conjunction with the aforemention'ed' dull previouslyimentioned mufiie is employed as an aid in' developing the duli, spangle free surface in connection with the use' of sulphur and sal ammoniac at the roughened exit roll, it becomes advisable to empioy a higher name or 'operate the mume at somewhat higher than ordinary temperature 'in order to counteract the brightening effect of the sal ammoniac and sulphur treatment.

It will become apparent that under the present invention 'of providing roughened exit rolis in the galvanizing pot, there are produced sheets free from the usual inclusions of foreign particles and surface imperfections which have, since the originof the galvanizing processes, been the cause of high rejections, excessive costs'and delayed deliveries. Also, by providing the knurled or shot blasted exit rolis, the surfaces of said rolls remain cleaner during operation and produce cleaner zinc coated products and eliminate the imprints usually made upon the sheet by grooved-exit rolis.

While I have shown and described specific embodiments of the presentinvention. it will be seen that I do not wish to be limited exactly thereto, since various modiflcations may be made "without departing from the s'cope of the invention, as deflned by the following claim.

I claim: 4

In a. galvanizing pot containing molten ga1- vanizing metal, the combination with means for\ conveying sheets through said metal, of a pair well as circumferentially of the roll surface to provide a self-rinsing action in contact with the sheet in the moiten metal, said rolls being loosely mounted' so as to only exert sulcient pressure upon the sheets to move the latter therebetween.

BAMUEL H. BOBROV. 

